In a group call service a large number of group participants are usually concentrated in a small geographical area, e.g., a construction site. Setting up multiple point-to-point communication links for such group participants, who may be located in a single sector, is not feasible. The group participants could “hog” up all the resources available for that sector. This would cause a very high call-blocking rate experienced by other users. In addition, if the concentration of the group participants is high in a given sector, the network may not have enough resources to assign a dedicated channel to every group participant. Therefore, users may be denied access to the group call not because of having group membership problems but because of lack of available network resources. This problem creates a negative impact on the group call users.
Existing group call services require a group call server to replicate the media and transmit one copy to each group participant on individual point-to-point communication links. Having the group call server to replicate the media for transmission to all participants of a target group is a processor-intensive task and could be quite taxing on the server when the number of group participants is large. Having the group call server to send one copy of the media to each group participant increases network traffic on both the wireless infrastructure's radio access network (RAN) and the service provider's wide area network (WAN).
For example, a class of wireless services is intended for quick, efficient, one-to-one or one-to-many (group) communication. In general, these services have been half-duplex, where a user presses a “push-to-talk” (PTT) button on a phone/radio to initiate a group call. If granted the floor, the talker then generally speaks for a few seconds. After the talker releases the PTT button, other group members can request the floor. These services have traditionally been used in applications where one person, a “dispatcher,” needs to communicate to a group of people, such as field service personnel or taxi drivers, which is where the “dispatch” name for the service comes from. Similar services have been offered on the Internet and are generally known as “voice chat.”
There is a need, therefore, for mechanisms to save radio resources, to reduce the processing load of the server, and to reduce network traffic of both the wireless infrastructure's RAN and the service provider's WAN.